This invention generally relates to carriers and laminates used in the production and application of decorative graphics to be adhesively applied and methods of making and using the same. More particularly, the invention provides a substantially transparent carrier for graphics to be applied to a substrate, the carrier having a film with an adhesive thereon which has a peel strength which decreases with increasing temperature and which allows the carrier to be immediately removed from just-adhered graphics.
Quick, easy and inexpensive methods of applying decorative graphics to a variety of substrates have long been desired. Examples of known methods of attaching decorative emblems and letters include sewing and the use of adhesives. The use of adhesives has been particularly practiced in the application of decorative graphics to fabric substrates of the type commonly found in sportswear and athletic garments such as team uniforms, jerseys, jackets and caps. Other examples of suitable garments capable of decoration with adhesively applied graphics are shorts, pants, T-shirts, sweatshirts, etc. Although the decorated garments must be highly durable and resistant to rough use, the cost of applying the graphics per garment must be low in terms of both time and money because of the large number of garments typically involved.
In general, the prior art has been unable to provide a single carrier capable of multiple advantages, i.e. (1.) holding a material from which a graphic may be cut securely enough to permit the cutting of intricate shapes therefrom with a computer guided blade, (2.) being adapted to retain a graphic thereon for transfer to a substrate on which the graphic is to be adhered, (3.) providing quick and easy registration of the graphic with respect to the desired location and orientation of the graphic on the substrate and (4.) simultaneously providing the capability of immediate removal of the carrier from the just-adhered graphic and underlying substrate without any damage to either. The later feature requires a minimization of the force required to remove the carrier from the graphic adhered substrate. Just-adhered graphics may be vulnerable to distortion and disruption from ripping or pulling forces employed to remove prior art carrier.
Thus, prior art carriers and laminates for use in the production and application of adhesively appliable graphics have generally been incapable of use with intricate cutting means and/or must be allowed to cool prior to removal from a graphic adhered substrate. While some paper coated release sheets do allow for immediate removal, they are limited to use with particular types of graphics. These paper carriers are often referred to as being capable of immediate or xe2x80x98hot peelxe2x80x99 removal because adherence of the graphic carried thereon to the substrate almost always requires the application of both heat and pressure. Thus, the graphic and underlying substrate are still hot when the paper carrier is immediately removed. Hot peel release of these paper carriers is generally facilitated by a change in the graphic material not the paper carrier. These paper carriers are opaque, however, making registration of the graphic to the substrate difficult. Also, they are generally incapable of serving as the carrier for a laminate from which intricate shapes can be cut with a computer controlled blade.
Several prior art patents have addressed these separate problems. For example, U.S. Pat. No. 3,660,212, issued to Liebe, Jr. and herein incorporated by reference, discloses heat applied athletic lettering having two layers of polyvinyl chloride bonded to each other. One of the layers of polyvinyl chloride is releasably adhered to a high gloss release paper sheet. Graphics are cut from the laminate and heat applied to the release coated paper sheet to cause one of the polyvinyl chloride layers to melt and encapsulate a desired fabric substrate.
However, the graphic material is generally not held securely enough to permit the formation of intricate detailed graphics.
More recently, U.S. Pat. No. 5,112,423 to Leibe, Jr. discloses an alignment maintaining plastic lettering material having three layers. The first layer is comprised of a pigmented display layer of a particular vinyl composition having first and second surfaces. On the first surface of the vinyl layer is a translucent release sheet of heat stabilized polyester onto which the vinyl layer has been solution cast. On the second surface of the vinyl lies a layer of non encapsulating thermoplastic adhesive, which is used to adhere the graphic to the substrate. It is believed that the release sheet of the Leibe, Jr. invention may not be removed until it has cooled to approximately room temperature.
U.S. Pat. No. 4,423,106 issued to Mahn discloses a laminated web consisting essentially of a polyester adhesive bonded to an extruded and rolled polyurethane lettering layer. The polyester layer is covered with a removable release sheet. The paper cover is removed, characters are die cut out of the web, the polyester adhesive layer is placed against a fabric substrate, a release coated paper cover is placed over the polyurethane layer and heat and pressure are applied. The melting point of the polyester adhesive is lower than of that of the polyurethane, so the polyester melts into the fabric to adhere the polyurethane graphic to the substrate.
Thus, despite the teachings of the prior art there remains the problem of being able to (1.) make decorative graphics from a laminate wherein the graphics are retained on the carrier of the laminate in an orientation which is a reverse or mirror image of the intended orientation of the graphic on the substrate, (2.) subsequently use the same laminate carrier to apply the graphic in a manner which allows the user of the carrier to see just how the graphics will appear on the substrate before they have been adhered thereto, and (3) have the option of immediately removing the same laminate carrier from the just applied graphic. The prior art has failed to resolve these problems while simultaneously providing a carrier for decorative graphics which is highly efficient in terms of production volume, has significant economic advantages and provides high quality decorative graphics.
Finally, the prior art has failed to provide a carrier which can provide these advantages as part of a laminate and also prove advantageous in other embodiments. It would be desirable to have a substantially transparent carrier with an adhesive upon which pre-formed graphics could be arranged in an orientation reverse from that intended on the substrate, which could provide easy registration with the substrate, could be removed immediately after adherence of the graphic and could be removed with a minimum amount of upwardly applied force so as to not damage the just-adhered graphic or substrate.
Because such characteristics would provide significant commercial advantages in terms of ease of use, efficiency and economy, it is an object of this invention to provide a carrier for decorative graphics capable of providing these advantages.
In particular, it is an object of this invention to provide a carrier for adhesively applied graphics which is capable of adequately securing the graphic during the graphic formation and application processes but which may be immediately removed from a graphic adhered substrate, wherein the removal of the carrier is effected with substantially little or no damage to the just applied graphic.
It is a further object of the invention to provide a laminate from which decorative graphics may be cut where the laminate enjoys the same advantage of the carrier of the invention.
It is another object of the invention to provide a method of applying a graphic to a substrate wherein a preformed graphic may be applied to the carrier of the invention and retained thereon for quick and accurate registration on the substrate but wherein the carrier may be immediately removed from the graphic adhered substrate without the application of an upwardly directed force of a magnitude which would distort or damage the just-adhered graphic.
It is also an object of this invention to provide the carrier and laminates discussed above from which graphics having a wide variety of compositions may be formed and/or subsequently applied to a variety of different substrates.
Finally, it is an object of this invention to provide methods of making and applying multiple component and multi-colored graphics using the carrier of the invention.
The instant invention addresses the deficiencies of the prior art by providing a carrier for graphics adhesively applied to a substrate, the carrier having a plastic film having opposite surfaces and an adhesive having a peel strength which decreases with increasing temperature. The adhesive is on or in direct, contiguous contact with at least one surface of the plastic film. The plastic film with the carrier thereon is substantially transparent and is adapted to retain a graphic thereon for transfer to a substrate, said peel strength of the adhesive being sufficiently reduced with increased temperature that the carrier may be removed from a just applied graphic without damaging the graphic.
In general, the carrier adhesive will have a particular tack. As used herein, tack may be defined as the property of an adhesive which enables it to form a bond of measurable strength immediately upon contact with another surface. Tack may also be referred to as xe2x80x9cinstantaneousxe2x80x9d adhesion or may intuitively be recognized as the property of xe2x80x9cstickiness.xe2x80x9d In general, the carrier adhesive will have sufficient tack or stickiness so as to bond at room temperature, a material from which decorative graphics may be cut, securely enough to permit the cutting of intricate shapes, with the use of computer aided cutting means. However, at elevated temperatures of from 200xc2x0 F. to 350xc2x0 F., the tack will be substantially reduced or negligible to human touch.
Those skilled in the art will appreciate that peel strength is merely one measurable aspect of the general property known in the art as tack. In quantitative terms, the carrier adhesive will have a peel strength of between 4 to 20 ounces per square inch of width at room temperature. More preferably the peel strength will be from 5 to 10 ounces per square inch. Peel strength as used herein is defined as the force necessary to strip a piece of the carrier at a 180xc2x0 angle from a stainless steel panel at a pulling rate of 12 inches per minute as generally described in ASTM method D-903. Room temperature may be generally defined as from 60xc2x0 to 90xc2x0 F. When the carrier adhesive is exposed to temperatures of about 250xc2x0 F. or greater, generally up to 350xc2x0 F., the peel strength of the carrier adhesive will be substantially reduced. In particular, at such temperatures the peel strength will be less than 3 ounces per square inch of width and most preferably will be 1 ounce per square inch of width.
Thus, with the application of increasing temperatures, the stickiness or tackiness as measured by the peel strength of the carrier adhesive will decrease with increasing temperatures, such that at temperatures of 200xc2x0 F. or more the carrier adhesive is substantially non-sticky and has substantially no tack. As the elevated temperatures are removed and the carrier cools down to room temperature, the stickiness or tackiness of the carrier adhesion will increase to the levels previously enjoyed prior to the application of the elevated heat. It will thus be appreciated that the carrier adhesive as disclosed herein has a peel strength which reversibly decreases with increasing temperature. The carrier adhesive of the instant invention does not transfer any residue or xe2x80x9cstickinessxe2x80x9d to the graphic or desired substrate irrespective of its peel strength.
The carrier of the invention may be utilized in the form of a laminated web or laminate. Such laminates are eminently suited for use in the production of decorative graphics intended to be adhesively applied to a variety of substrates, and most preferably to fabric substrates. After the formation of the decorative graphic, the laminated web or laminate may be used as a means of adhering the graphic to a desired substrate.
The laminates will be comprised of the carrier of the instant invention, a substantially contiguous layer of a material from which a graphic may be cut which is positioned on the carrier adhesive, and a substantially continuous layer of a means for adhering a graphic positioned on the graphic material layer.
The graphic material may be a thermoplastic, a thermoplastic containing material, or a cuttable material such as paper. Preferably, the graphic material will be a thermoplastic layer. Most preferably it will be polyurethane film.
On top of this substantially contiguous layer of graphic material is a substantially contiguous layer of a means for adhering a graphic. The layer of graphic adherent means may be activated by heat, pressure or combinations of both. Most preferably, the graphic adherent means will be an adhesive activated by the application of both heat and pressure and most preferably by heat sufficient to cause temperatures of 200xc2x0 F. or more. In general, pressures anywhere between 1 to 20 pounds per square inch (psi) are suitable. Pressure of from 3 to 8 psi are most preferred.
However, even if the graphic adherent means may be actuated solely by pressure, i.e. a pressure sensitive adhesive, sufficient heat will still be applied so as reduce the peel strength of the carrier such that the carrier may be immediately removed from a just applied graphic without damaging the graphic. Typically, temperatures of from 200xc2x0 F. or more will be applied so as to reduce the peel strength to about 3 oz/in2 or less. Most preferably, temperatures of from 250xc2x0 to 350xc2x0 F. will be applied. It will be appreciated that because such application of heat is necessary for immediate removal of the carrier from a just adhered graphic, it is reasonable to use a graphic adherent means which is activated by in the same temperature range.
The laminated webs made according to the instant invention are particularly suitable when used in the process of making decorative graphics. Such laminates can be readily cut by cutting means well known in the art which will cut only through the layers of graphic material and graphic adherent means. The carrier of the instant invention comprised of the substantially transparent plastic film and carrier adhesive will not be cut through, although some scoring of the plastic film may occur.
Examples of suitable cutting means include carbide knives, laser cutting, kiss cuts, steel ruled dies, etc. Most preferably, computer controlled blades or knives will be employed to cut a reverse or mirror image graphic pattern or outline. Such graphic patterns may include intricate and/or small letters that may be either connected or separated from each other.
Those portions of the graphic material and graphic adherent means which are outside the outline of the decorative graphic will be peeled away from the carrier adhesive. Such processes may be defined as xe2x80x9cweeding outxe2x80x9d and may be successfully done with the use of small tools which exert sufficient force to pull the non-desired portions of the graphic material and graphic adherent mean layers away from the carrier adhesive.
The resulting web will be transparent except for those remaining portions of the graphic material and graphic adherent layers which form the graphic.
It will be appreciated that cutting means such as computer controlled blades or knives may be employed to cut intricate shapes out of the thermoplastic layer because of the strong adherence of the carrier adhesive at room temperature to the substantially contiguous layer of graphic material. In general, such adherence will result when the carrier adhesive has a peel value of from 4 to 20 oz/in2. Such valves will typically result when the most preferred carrier adhesive is at room temperature.
When it is desired to apply decorative graphics to a substrate, the transparent carrier is advantageous because it enables the instantaneous and completely accurate alignment of the many components of a multi-component decorative graphic. When the user of the carrier positions the carrier such that the graphic adherent layer is juxtaposed with respect to the substrate, the various components of the decorative graphic will be orientated with respect to each other just as they will be after the application. Registration of the overall graphic to the substrate can be accomplished quickly and easily because the carrier user can see the substrate through the substantially transparent carrier. Costly and almost impossible to fix mistakes in alignment caused by human error and movement of the substrates will be essentially negligible since human contact with the various graphic components and the substrate are minimized.
Those skilled in the art will appreciate that significant reductions in the time spent in preparing and positioning the decorative graphic on a substrate will be substantially reduced as compared to prior art methods. As long as the alignment and relationship of the decorative graphics is correct on the carrier adhesive, the desired relationship will be achieved on the substrate. It will be appreciated that when the carrier is viewed from the back, the graphic image will be in reverse. Alternatively, when the carrier is viewed from the front, the graphic will be orientated as it will appear after application.
As indicated above, most preferably, sufficient heat will be applied to the laminated web during graphic application, so as to cause the peel strength of the carrier adhesive to decrease to a value which is less than 3 ounce per square inch of width. Sufficient heat will be such as to cause the temperature of the carrier to be increased to 200xc2x0 F. or more. Most preferably, sufficient heat will be added so as to cause the carrier of the laminated web to be at a temperature between 300xc2x0 F. to 350xc2x0 F. In the absence of such heat and temperatures, the removal of the carrier of the instant invention will require the application of upwardly directed forces sufficient to overcome the maximum peel strength of the carrier to the just applied graphic.
Sufficient force in the form of heat, pressure or a combination thereof, will be applied to the laminated web when it is positioned on the substrate in order to activate the graphic adherent means. The graphic adherent means will preferably be selected so as to be activated by a combination of both. Most preferably, the graphic adhesive will be activated by a combination of heat between 300xc2x0 F. to 350xc2x0 F. and pressure of from 1 to 6 psi. In this most preferred instance, a combination of sufficient heat and pressure will be applied so as to cause the graphic adherent means to adhere the graphic material of the graphic to the desired substrate while simultaneously causing the peel strength of the carrier adhesive to decrease to a level of less than 3 ounces per square inch of width. However, those skilled in the art will appreciate that the graphic adherent means may be a pressure activated adhesive only.
It will thus be appreciated that heat will always be applied when using the carrier of the instant invention to provide the capability of immediate or hot peel removal of the carrier. Pressure may be applied as required for the activation of the graphic adherent mens. A particularly desirable means for applying heat or heat and pressure to the various embodiments of the instant invention is the heat sealing machine disclosed and illustrated in U.S. Pat. No. 5,167,750 to Myers, which is herein incorporated by reference. The heat sealing machine disclosed therein is capable of applying temperatures from 200 to 400xc2x0 F. and pressure from 0 to 4.5 psi. Other heat sealing machines of this type capable of exerting pressures of up to 15.6 psi may be used with the instant invention.
In an alternative embodiment, the carrier of the invention may be utilized as a means for applying previously cut or formed graphics. In such an embodiment, the decorative graphics and/or lettering may be comprised of a variety of materials including but not limited to thermoplastic, fabrics, cloth, paper and combinations thereof. Examples of suitable thermoplastics are polyurethane and vinyl as well as thermoplastic mixtures having ingredients which upon exposure to heat or pressure expand in size. It will be appreciated that the latter are known as puff type thermoplastic mixtures.
Examples of suitable fabrics are twill, cotton, and felt. A particularly suitable form of fabric lettering is set forth in U.S. Pat. No. 5,149,388 to Stahls"". Flock materials such as those commonly known in the art and discussed in U.S. Pat. No. 5,047,103 to Abrams may also be utilized. It will be appreciated that numerous other types of materials may be suitable for use as precut decorative graphics.
The precut decorative graphics whether comprised of thermoplastic, fabric, flock, paper or combinations thereof will have a layer of graphic adherent material positioned on the side of the graphic material opposite from that which is in contact with the carrier adhesive. The graphic adherent means will be such as disclosed immediately above with respect to the laminated web.
When the carrier of the instant invention is utilized as a means for adhering precut decorative graphics, the decorative graphics will be applied to the carrier adhesive in an orientation which is a reverse or mirror image of that desired on the substrate. When the user of the carrier desires to apply the graphics to a substrate the carrier will be turned over such that the graphic adherent layer of the pre-cut graphic is immediately parallel to the desired substrate. Thus, the user looking down will see the decorative graph in the xe2x80x9ccorrectxe2x80x9d orientation, i.e., as desired on the substrate. The carrier will then be lowered and positioned so that the graphic adherent means is in intimate contact with the desired substrate. Application of sufficient force such as heat, or heat and pressure will cause the graphic adherent means to be activated so as to adhere the precut decorative graphic to the desired substrate and allow for the immediate removal of the carrier from the just applied graphic without damaging the graphic.
Finally, it is possible with the instant invention to provide a methods of making and applying multiple component decorative graphics having graphic material components of different colors or compositions. Two methods are contemplated.
First, the carrier of the instant invention may be used to apply a first decorative graphic to a temporary support structure. The temporary support structure will be a material which will have a bond strength with the graphic adherent which is greater than the bond strength between the graphic material and the carrier adhesive when the carrier adhesive is at elevated temperatures of from 200xc2x0 F. or more. However, this same temporary support structure must have a bond strength with the graphic adherent means which is less than the bond strength between the graphic material and the carrier adhesive when the carrier adhesive is at room temperature. The temporary support structure will preferably be a paper sheet having a release coating thereon.
The carrier is removed immediately after the application of sufficient heat or heat and pressure to cause the graphic to be adhered to the temporary support structure and the peel strength of the carrier adhesive to be sufficiently reduced so as to allow immediate removal of the carrier without damage to the graphic. Typically this will occur when heat from 200 to 350xc2x0 F. is applied and the peel strength of the carrier is reduced to less than 3 ounces per square inch and most preferably, less than 1 ounce per square inch.
Subsequently, a second decorative graphic is applied to the temporary support structure having the first graphic adhered thereon. It may be applied directly on to the upper surface of the first decorative graphic previously adhered to the temporary support. Alternatively, it may be positioned so as to be overlapping or in close proximity to the first decorative graphic. Such considerations are limited only by the imagination of the carrier user.
After the application of sufficient heat and/or pressure to cause the second decorative graphic to adhere to the first decorative graphic, the entire assembly is allowed to cool without the carrier being removed from the second decorative graphic. The resulting structure of the temporary support structure, the various graphic components and the carrier of the instant invention may be termed a decorative composite. As the temperature of the decorative composite is allowed to cool, the peel strength of the carrier adhesive increases. When the temperature of the decorative composite is approximately room temperature, the temporary support structure is removed from the composite, leaving both the second and first decorative graphics adhered to each other and/or to the carrier adhesive of the carrier. Subsequently, the first and second decorative graphics adhering to the carrier adhesive may be applied to a substrate, such as a fabric substrate. Upon the application of sufficient heat or heat and pressure, the graphic adherent means of both the first and second decorative graphics will adhere to the desired substrate and the carrier will be capable of immediate removal. Immediately after the application of sufficient heat, the carrier may be removed from the surface of the first and second decorative graphics without damage thereto. Those skilled in the art will appreciate that carrier removal may be delayed until the carrier cools to room temperature so long as the bond strength of the graphic adherents and substrate is greater than the bond strength of the graphic material and the carrier adhesive at room temperature.
Alternatively, such multiple component, multi-colored decorative graphics may be prepared immediately and directly upon the desired substrate using sequential applications. In such cases, the first decorative graphic will be applied to the desired substrate in a registered fashion corresponding to that of the ultimately desired location of the graphic on the substrate. With the application of sufficient heat or heat and pressure, the substantially negligible force required to remove the carrier from the first adhered graphic results in almost no displacement or distortion of the underlying substrate or to the adhered graphic. As a result, a second decorative graphic, will be positioned on or by the first adhered graphic. If the second graphic is on the first graphic, the adherent means of the second graphic will be in intimate contact with the decorative graphic material of the first adhered graphic. Sufficient heat or heat and pressure will be applied so as to cause the graphic adherent layer of the second decorative graphic to adhere to either the surface of the first decorative graphic or the substrate and the peel strength of carrier adhesive to simultaneously decrease so as to allow for immediate carrier removal.
Immediately after said application of heat, the carrier is removed with substantially negligible upward applied force. As a result, the multi-colored and/or multiple component decorative graphic may be assembled directly onto a desired substrate. When the carrier is immediately removed, little or no distortion of or damage to the underlying substrate or adhered graphics occurs. As a result, no misalignment of subsequently applied decorative graphics occurs. The use of the transparent carrier facilitates the positioning of the one or more decorative graphics upon the underlying substrate.